The official website of the MISRA association https://www.misra.org.uk/ has
many freely available resources about MISRA C, some of which can be downloaded
after registering on the MISRA Bulletin Board at
https://www.misra.org.uk/forum/ (such as the examples from the MISRA C:2012
standard, which includes a one-line description of each guideline).

The following documents are freely available:

MISRA Compliance 2016: Achieving compliance with MISRA coding guidelines,
2016, which explains the rationale and process for compliance, including a
thorough discussions of acceptable deviations

The main MISRA C:2012 document can be purchased from the MISRA
webstore.

PRQA is the company that first developed MISRA C, and they
have been heavily involved in every version since then. Their webpage
http://www.prqa.com/coding-standards/misra/ contains many resources about
MISRA C: product datasheets, white papers, webinars, professional courses.

An introduction to MISRA C:2012 at
http://info.prqa.com/MISRA C-2012-whitepaper-evaluation-lp

The Myth of Perfect MISRA Compliance at
http://info.prqa.com/myth-of-perfect-MISRA Compliance-evaluation-lp,
providing background information on the use and limitations of static
analyzers for checking MISRA C compliance

A student-oriented textbook on SPARK is Building High Integrity Applications
with SPARK by John McCormick and Peter Chapin, published by Cambridge University
Press. It covers the latest version of the language, SPARK 2014.

A historical account of the evolution of SPARK technology and its use in
industry is covered in the article Are We There Yet? 20 Years of Industrial Theorem
Proving with SPARK by Roderick Chapman and Florian Schanda, at
http://proteancode.com/keynote.pdf

The booklet AdaCore Technologies for CENELEC EN 50128:2011 shows how
AdaCore's technology can be used in conjunction with the CENELEC EN 50128:2011
software standard for railway control and protection systems. It describes
in particular where the SPARK technology fits best and
how it can be used to meet various requirements of the standard. See:
https://www.adacore.com/books/cenelec-en-50128-2011/.

The booklet AdaCore Technologies for DO-178C/ED-12C similarly shows how
AdaCore's technology can be used in conjunction with the DO-178C/ED-12C
standard for airborne software, and describes in particular how SPARK
can be used in conjunction with the Formal Methods supplement DO-333/ED-216.
See https://www.adacore.com/books/do-178c-tech/.